1. Field of the Invention
The present invention relates to the field of DC to DC converters.
2. Prior Art
The preferred embodiment of the present invention pertains to DC-DC buck (step-down) converters. These are switching regulators that switch one end of an inductor between the input power supply and ground. The inductor spends T.sub.ON seconds connected to the input power supply and the remainder of the time connected to ground. If T is the total time for one cycle, then the output voltage (at the other end of the inductor), if filtered, will average T.sub.on /T.times.V.sub.IN.
Filtering normally entails connecting a capacitor from the output side of the inductor to ground. The amount of ripple voltage at the output varies with V.sub.IN, T, L, C and V.sub.OUT.
A dual interleaved converter uses two buck converters running in parallel, but switched 180.degree. out of phase. Thus halfway through the first cycle of one inductor, the second inductor is switched high (to V.sub.IN). For given values of L and C, the dual interleaved converter has two advantages:
1. The ripple at the output is at least four times smaller than with the single inductor approach. PA1 2. If designed to have the same ripple at the output, the dual-interleaved design has a response time to load changes that is at least eight times faster than the conventional design.
While dual interleaved converters are known in the prior art, such converters have not been realized in integrated circuit form because of various problems with dual interleaved converters which are not easily overcome in integrated circuit form, including but not limited to keeping inductor currents balanced.